1. Field of the Invention
The present invention relates to an exhaust gas recirculation system (EGR system) for an internal combustion engine.
2. Description of the Related Art
In general an exhaust gas recirculation system for an internal combustion engine has such a configuration that EGR gas to be recirculated is extracted from an exhaust port in a cylinder head and is led into an intake passage, downstream of a throttle valve, by way of an EGR valve.
In the exhaust gas recirculation system having the above-mentioned configuration, when an intake manifold is made of resin, for preventing thermal deformation of the resin manifold caused by EGR gas at a high temperature, a metal spacer (plate) is interposed between the resin intake manifold and the cylinder head of the engine, and an EGR gas passage is formed in the spacer portion.
As a conventional structure forming the EGR gas in the spacer portion, as shown in FIG. 12, an EGR branch passage 102 which is recessed in a spacer 101 and through which EGR gas flows upward is disclosed, for example, in JP-A-2000-8968.
As the above-mentioned conventional exhaust gas recirculation system, in the configuration that the EGR branch passage 102 in the spacer 101 is curved downward in a state of installation, condensed water from steam in EGR gas collects at a bottom portion 103 of the EGR branch passage 102, and there would be caused a risk of corrosion of the spacer 101 due to aging effect since the condensed water is acid.